We study the naturalness of electroweak symmetry breaking and baryogenesis in the next-to-minimal supersymmetric standard model (NMSSM). Our study is motivated by the recent LEP bounds on the Higgs boson mass which severely constrains the low \tan\beta region of the minimal supersymmetric standard model (MSSM). We show that the low \tan \beta region of the NMSSM is clearly favoured over the MSSM with regard to the physical Higgs boson mass, fine-tuning, and electroweak baryogenesis.Comment: 17 pages, Latex, 3 eps figures, typos corrected, reference adde

Abstract:We update the constraints on two-Higgs-doublet models (2HDMs) focusing on the parameter space relevant to explain the present muon g − 2 anomaly, ∆a µ , in four different types of models, type I, II, "lepton specific" (or X) and "flipped" (or Y). We show that the strong constraints provided by the electroweak precision data on the mass of the pseudoscalar Higgs, whose contribution may account for ∆a µ , are evaded in regions where the charged scalar is degenerate with the heavy neutral one and the mixing angles α and β satisfy the Standard Model limit β − α ≈ π/2. We combine theoretical constraints from vacuum stability and perturbativity with direct and indirect bounds arising from collider and B physics. Possible future constraints from the electron g − 2 are also considered. If the 126 GeV resonance discovered at the LHC is interpreted as the light CP-even Higgs boson of the 2HDM, we find that only models of type X can satisfy all the considered theoretical and experimental constraints.

We systematically analyze the correlations between the various leptonic and hadronic flavor violating processes arising in SUSY Grand Unified Theories. Using the GUT-symmetric relations between the soft SUSY breaking parameters, we assess the impact of hadronic and leptonic flavor observables on the SUSY sources of flavor violation. I. INTRODUCTIONSupersymmetry (SUSY) Breaking (SB) remains one of the biggest issues in physics beyond the Standard Model (SM). In spite of various proposals [1], we still miss a realistic and theoretically satisfactory model of SB.Flavor violating processes have been instrumental in guiding us towards consistent SB models.Indeed, even in the absence of a well-defined SB mechanism and, hence, without a precise knowledge of the SUSY Lagrangian at the electroweak scale, it is still possible to make use of the Flavour Changing Neutral Current (FCNC) bounds to infer relevant constraints on the part of the SUSY soft breaking sector related to the sfermion mass matrices [2].The model-independent method which is adopted is the so-called Mass-Insertion Approximation * Unité mixte du CNRS et de l'EP, UMR 7644.

This chapter of the report of the "Flavor in the era of the LHC" Workshop discusses the theoretical, phenomenological and experimental issues related to flavor phenomena in the charged lepton sector and in flavor conserving CPviolating processes. We review the current experimental limits and the main theoretical models for the flavor structure of fundamental particles. We analyze the phenomenological consequences of the available data, setting constraints on explicit models beyond the standard model, presenting benchmarks for the discovery potential of forthcoming measurements both at the LHC and at low energy, and exploring options for possible future experiments.

That µ → e, γ and τ → µ, γ are sensitive probes of SUSY models with a see-saw mechanism is a well accepted fact. Here we propose a 'top-down' approach in a general SUSY SO(10) scheme.In this framework, we show that at least one of the neutrino Yukawa couplings is as large as the top Yukawa coupling. This leads to a strong enhancement of these leptonic flavour changing decay rates. We examine two 'extreme' cases, where the lepton mixing angles in the neutrino Yukawa couplings are either small (CKM-like) or large (PMNS-like). In these two cases, we quantify the sensitivity of leptonic radiative decays to the SUSY mass spectrum. In the PMNS case, we find that the ongoing experiments at the B-factories can completely probe the spectrum up to gaugino masses of 500 GeV (any tan β). Even in the case of CKM-like mixings, large regions of the parameter space will be probed in the near future, making these two processes leading candidates for indirect SUSY searches. * Electronic address: masiero@pd.infn.it † Electronic address: vempati@pd.infn.it ‡ Electronic address: vives@thphys.ox.ac.uk